myRIO measuring rs 257-133 flow measurement

[johnlr]

Hi,

Hoping to get help with an issue I'm having. I'm a labview beginner and I'm trying to get flow readings from an RS 257-133 flow meter through a myRIO. I have created a VI that measures the pulses from the turbine through an encoder by counting them. I need to convert this to an outputted flow rate in labview, so I need to measure the frequency. I built on an existing myrio encoder VI from the "myRIO project essentials guide" and I thought maybe inputting the count from the encoder into the express vi "timing and transition measurements" might do it but it does not. Like I said I'm a beginner so have just been trying different things in the hope I get lucky. I've attached the VI I'm working on.  Would anyone know how to do this? Thanks

[GerdW · Accepted solution]

Hi johnlr,

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@johnlr wrote:

I thought maybe inputting the count from the encoder into the express vi "timing and transition measurements" might do it but it does not. Like I said I'm a beginner so have just been trying different things in the hope I get lucky.

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To know a pulse frequency you need to know the number of pulse measured within a period of time.

Your loop is already set to iterate at a certain period of time. Now all you need is the number of pulse within that time: it's the difference between previous count and actual count!

Like this:

Edit: there's a small bug, you need to divide that "10ms" by 1000 instead of multiplying to get "0.01s"…

[johnlr]

Hi GerdW,

Thank you so much for your help. Your solution got me the pulse frequency and then I managed to convert that to a flow rate. I now have the Labview reading the flow meter and giving a calculated flow rate.

Thank you very much again!

johnlr

[Dr.XGenji]

• Hello sir, Can you show me the schematics, diagram circuit or picture connection of RS 257-133 please ? Thank you.